<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
    .box{   width: 50px;
            height: 50px;
            background: #eee;
            margin: 0 auto;
        }
    </style>
</head>

<body>
        <div class="box">box</div>
        <script type="text/javascript">
            var box = document.getElementById('box');
            var i = 0;
            box.onclick = function(){
                ++i;
                if(i%2){
                    this.style.width = '200px';
                    this.style.height = '200px';
                    this.innerHTML = '大';
                }
                else{
                    this.style.width = '50px';
                    this.style.height = '50px';
                    this.innerHTML = '小';
                }
            };
        </script>
</body>
</html>